The present invention relates to a rotary cutting device in general, and to a rotary handpiece having a rotating blade or similar for cutting a variety of materials in particular. More particularly, the present invention relates to a hand held cutting device for use in the cutting and shearing industries, such as for example for shearing hair, fur, wool or the like from animals or humans, or for cutting other natural or synthetic materials such as metals, paper, textiles, fibres and the like. The handpiece is provided with a rotary cutting member in the for of a planar blade and a plurality of cutting elements in the form of elongate chips or blades which co-operate with the rotating blade so that material such as wool fibres or the like when located between the rotating planar blade and the chips is cut or severed. Even more particularly, the present invention relates to improvements in the handpiece by providing the handpiece with an adjustable tensioning means for adjusting the tension of the rotary cutting assembly, particularly the tension applied to the rotary planar blade in order to alter the cutting characteristics of the handpiece.
Although the present invention will be described with particular reference to a rotary handpiece for shearing sheep, in which the rotary handpiece has a cutting assembly comprising a planar rotating cutting member, a replaceable cartridge containing a plurality of cutting elements or chips and a means for adjusting the tension of the rotary cutting assembly, it is to be noted that the scope of the present invention is not limited to the described arrangement or embodiment but rather the scope of the invention is more extensive so as to include other arrangements of the rotary handpiece and uses for the rotary handpiece in other applications than those specifically described and to the use of the rotary handpiece for cutting a wide variety of diverse materials.
Additionally, it is to be noted that although the invention will be described with particular reference to a hand held headpiece, the present invention also applies to other forms of the handpiece having the cutting assembly, such as, for example, a robotically controlled handpiece having different forms of the cutting assembly, handpieces and cutting assemblies located at the end of a mechanical arm or similar, cutting assemblies provided with automatic shearing machines, and the like.
Currently, shearers almost universally use handpieces of the reciprocating or oscillating type, which have a fixed comb and a moveable cutter held in intimate contact with each other by a strong compressive force between the two. As the cutter reciprocates or oscillates in intimate contact with the fixed comb, material located between the cutter and comb is cut. However, as the cutter and comb must be held together with such force, heat due to friction between the two components is produced. This unwanted production of heat is undesirable.
Other disadvantages of conventional handpieces are caused by the cutter mechanism itself and the arrangement of the various components. The limitations of the reciprocal or oscillating motion are well known and include the problems of the cutter producing vibrations within the handpiece as it oscillates; heat build up due to frictional forces; the cutters and combs requiring regular replacement or sharpening; the need to provide sufficient lubrication; injury to and burning of the sheep and on occasions, the shearer; and, should the handpiece be dropped or knocked from the shearer""s hand it can often continue operating in an out-of-control manner which is extremely dangerous for persons or animals in close proximity to the handpiece and may result in damage to the handpiece. In these cases the handpiece must be disconnected from its driving means before it can be approached and ultimately retrieved.
Efforts have been made in recent times to provide a handpiece having vibration characteristics which are less likely to cause injury and which are safer to use than conventional handpieces; which can operate at a lower temperature; which require no or little lubrication; and which are less likely to cause injury to shearers, shed personnel and to the sheep. Australian provisional patent application No. PN0883 amongst other applications describes a rotary handpiece which contributes significantly to overcoming the problems associated with the oscillating handpieces of the prior art. The rotary handpieces of Australian provisional patent application No. PN0883 have blades and chips which have a longer useful working life than those know previously, are relatively cheaper to maintain and are of such low cost that they maybe discarded when blunt and no longer serviceable and replaced by new blades or other cutters so that resharpening of the blades is not required. The rotary handpiece can be Mastered quickly even by novices. Co-pending Australian provisional patent application by the same applicant provides a rotary handpiece which comprises a rotary cutting member and a replaceable cartridge comprising a plurality of replaceable cutting elements or chips which co-operate with the rotary cutting member to sever material such as wool. The cartridge can be quickly and easily replaced as the chips become blunt and/or damaged and/or lost.
While these rotary handpieces provide important and useful advances over the cutting devices of the prior art, it has not hitherto before been possible to easily and quickly modify the action of the rotary cutting member in relation to the cutting elements to allow for use of the rotary handpiece to cut a wide variety of different types of materials requiring different cutting characteristics For example a shearer may want to modify or adjust the action of the rotary cutting member with respect to the cutting elements to allow for the different physical properties of different classes of wool or other materials using the one handpiece, such as, for example, to accommodate different grades of fineness of the wool, say from very fine to very coarse, and wool of different conditions, such as wool full of contaminants such as dirt particles, grass seeds, burrs and the like. Additionally, the handpiece may be used on cattle to shear hair from a cut line to clean the cut line of debris before the cattle is slaughtered in an abattoir. Thus, there is a need to be able to alter the cutting characteristics of a handpiece so that the one handpiece can be used to cut a wider variety of different and diverse materials, such as for example the range of different wool fibres and types of the various species of sheep and the hair or fur of other animals such as cattle, goats and the like. It has now been found that a rotary handpiece can be provided which allows the user to modify the cutting characteristics of the rotary cutting member and/or cutting element(s) quickly and easily by altering the tension of the rotary cutting assembly, particularly the tension applied to the rotary cutting member.
Thus, it is an aim of the present invention to provide a rotary handpiece provided with means for modifying the cutting characteristics of the handpiece, such as for example by providing the handpiece with an adjustable tensioning means for altering the tension applied between the rotating blade and the individual elongate cutters in order to accommodate a wider variety of different materials and/or different grades or thicknesses of the one material.
According to the present invention there is provided a rotary handpiece suitable for cutting or severing a material comprising:
a cutting member capable of rotary motion in a first direction, and
at least one cutting element capable of substantially linear movement in a second direction, said motion in the first direction being different to the direction of movement in the second direction, and
an adjustable tensioning means,
wherein the cutting member and the cutting element are arranged such that the cutting member and cutting element co-operatively interact with each other in use to cut material located therebetween and wherein tension applied to the-cutting member can be adjusted by the adjustable tensioning means to alter the clearance of and the amount of contact between the cutting member and the cutting element in order to alter the cutting characteristics of the handpiece.
Typically, there is a plurality of substantially similar cutting elements, preferably elongate, grooved cutting chips having angularly inclined faces. More typically, the plurality of cutting elements are individually mounted on within a cartridge. Even more typically, the cartridge is a replaceable cartridge. Even more typically, the replaceable cartridge comprises a body portion having a plurality of recesses in which each recess is adapted to receive individual elongate cutting elements so that at least one angularly inclined cutting surface is exposed for contact With the cutting member. Even more typically, the cutting elements are individual cutting chips which can readily be replaced by new chips when worn, blunt or damaged.
Typically, the replaceable cartridge is provided with a body portion and forwardly directed projections. Typically, the recesses in the cartridge are located such that when a cutting element is located in the recess, the cutting element extends in the direction of the projection, that is, radially outwardly directed from the curved body portion. Typically, the cutting elements are removably held within the recesses by interference fit, a keyway, a positive retention means, a spring or biasing means, or the like. Typically, the cutting elements are readily replaceable so that should a cutting element become broken or damaged, it may be easily removed, such as for example by being levered out of the recess using a suitable implement such as a fingernail or similar tool, and discarded before being replaced with a new cutting element. If several cutting elements need replacing simultaneously, the cartridge may be removed from the handpiece and discarded and a new cartridge containing a fresh set of cutting elements inserted in the handpiece.
Typically, the rotary handpiece comprises a handle, a hub, a body portion and a guide means. The guide means typically comprises a plurality of narrow, elongate fingers which form a comb for guiding the rotary handpiece along a predetermined pathway through the material being cut, such as for example wool, fur, hair or the like. Typically, the guide means is integral with the body portion. Typically, the cutting member and the cartridge are removably mounted or connected to the body of the rotary handpiece. More typically, the fingers direct material to be cut towards the cutting member and cutting chips to effect cutting of the material in use of the handpiece.
Typically, the cutting member is a substantially planar rotary blade, such as, for example, in the form of a rotatable disc having a plurality of generally radially directed cutting surfaces in the form of teeth. More typically, each individual tooth is generally arcuate in which at least one of the leading edge or the trailing edge of the tooth is curved, preferably both trailing and leading edges being arcuate. More typically, each tooth has a leading edge and a trailing edge shaped so that the teeth are swept back with respect to the normal direction of rotation of the blade in use. Even more typically, the teeth are radially arcuately curved. Even more typically, both the leading and trailing edges of the teeth are curved in the same direction. Typically, the rotary blade is resiliently mounted or connected to the handpiece by a mounting means or connection means in such a manner so as to permit rotary movement of the cutting member with respect to the body of the rotary handpiece and the mounting means or connection means. Typically, the rotation of the rotary blade causes individual teeth of the rotary blade to contact individual chips in turn to move the chips linearly backwards in use of the handpiece to cut material located between the blade and the cutting element.
Typically, the tension on the rotary blade is applied by a tensioning means. More typically, the tensioning means includes a blade retainer plate. More typically, movement of the blade retainer plate alters the degree of tension applied. Even more typically, the blade retainer plate is rotatable to adjust the tension. More typically, the tension on the rotary blade is readily adjusted using a spanner or other tool to rotate the blade retainer plate, or the blade retainer plate is manually adjustable. Typically, the rotary blade is connected to a hub axle by the blade retainer plate which is provided with a centrally located externally threaded boss which is threadingly received into a correspondingly threaded internal bore located at the end of a spindle, which in turn screws into the hub axle, thus allowing rotary motion of the spindle and all the components connected thereto, including the rotary blade.
Typically, the tension on the rot blade can be adjusted using an adjustment means comprising the espindle, a flanged ember and a bearing provided with a resilient element. Typically, the resilient element is located between the flanged member and the bearing. Typically, as the blade retainer plate is screwed into the end of the spindle, the distal and surface of the spindle end bears down on the flanged member which concomitantly compresses the resilient element against the bearing. More typically, the resilient element is an O-ring or similar. The use of an O-ring or the like provides a flexible or resilient body against which the tension on the cutting member may be adjusted.
Typically, the tension on the cutting member cay be continuously adjusted, i.e. stoplessly between the limits, or alternatively the adjustment of the tension on the cutting member may be incremental, i.e. Stepwisely using a ratchet mechanism or similar to adjust the tension by a preselected amount each time. Preferably the ratchet mechanism or the like incorporates detents or audible xe2x80x9cclicksxe2x80x9d so that the user can better measure or judge the amount of increase or decrease in tension to be applied to the rotary blade as the blade retainer plate is screwed into or out of the spindle.
Typically, the cartridge comprises a biasing means. In use the biasing means provides bias between the cartridge and the body of the rotary handpiece. Typically, the biasing means, comprises a piece of resilient material such as rubber or plastics or polymeric material, particularly plastic or polymeric tubing. Typically, the biasing means is held by interference fit in an elongate depression in the body of the cartridge. It will be readily appreciated by those skilled in the art that different biasing forces can be achieved by using materials of different resiliency. Typically, the biasing means comprises a piece of polymer tubing such as surgical tubing located in a shallow, curved depression in thee body portion of the replaceable cartridge.
Typically, where the cartridge comprises a biasing means the biasing means acts to bias or retain the cutting elements in the recesses of the body portion. More typically, where the cutting elements comprise triangular prism like shaped chips, one apex of the chips is in contact with the biasing means and the biasing means acts to retain the prism in the recess in the body portion.
Typically, the elongate cutting element or chip used in the handpiece of tile present invention is generally triangular prism shaped blade or chip. More typically, the cutting element is arranged so that in the normal in use position of the cutting device the base of the triangular blade or chip is oriented towards the cutting surfaces of the rotary blade. More typically, the cutting element is provided with a cutting surface which is in contact with the cutting surface of the teeth of the rotary blade.
Typically, where the cutting element is a triangular prism like shaped chip, the chip is provided with a number of surfaces which are parallel to each other. More typically, all but one of the surfaces are parallel. Most typically, the surface which is not parallel to the other surfaces is a tapering surface or an oblique surface arranged to extend at an acute angle to the parallel surfaces.
The cutting elements such as chips may comprise any convenient material and be manufactured by any convenient means. For example the cutting elements may comprise metal or synthetic material such as plastics or polymers, or may comprise a mixture of components such as polymer coated metal. The cutting elements may for example, be manufactured by cutting metal rod, bent sheet metal, metal pipe or the like.
The rotary handpiece of the present invention may be operated by any suitable means or method known in the art. One typical method of operation is described in Australian provisional patent specification No. PN0833. Typically, a drive shaft is rotated by suitable driving means which in turn rotates pinion and meshed gear thus turning an axle hub which causes the cutting means to rotate.